Automatic tooth brush



Feb. 8, 1966 w. HARTMANN AUTOMATIC TOOTH BRUSH 2 Sheets-Sheet 1 Filed April 7, 1964 FIG] 6 mmuL y Feb. 8, 1966 w. HARTMANN AUTOMATIC TOOTH BRUSH 2 Sheets-Sheet 2 Filed April '7, 1964 I INVENTOR l HQf/l'h 201-7 ATTORNEY United States Patent 3,233,265 AUTOMA'HC TGGTH BRUSH Willy Hartmann, Stuttgart-Weilimdorf, Germany, assignor to Alfred Paul K.G., Esslingen-Zell, Germany Filed Apr. 7, 1964, Ser. No. 357,935 Claims priority, application Germany, Apr. 13, 1%3, P311591 20 Claims. (Cl. 15-22) The present invention relates to tooth brushes in general, and more particularly to an automatic power-operated tooth brush which, in addition to being useful as a means for performing the customary tooth cleaning action, also serves as a highly effective massaging device for the gums.

The concept of utilizing a small electric motor which receives current from batteries and which causes a brush member to vibrate while its bristles are in contact with the teeth is known for many years and various types of such automatic tooth brushes are available on the market. My present invention relates to improvements in such tooth brushes and one of its principal objects is to provide a power-operated tooth brush, including a brush member and means for imparting various movements thereto, which is constructed and assembled in such a way that the massaging action of the bristles is particularly beneficial to the gums, that such massaging action may be attained without affecting the cleaning action of the bristles, and that the upper and lower gums are massaged in a predetermined sequence and in a predetermined direction.

Another object. of the invention is to provide an automatic tooth brush of the just outlined characteristics which is constructed and assembled with a view to insure that the gums may be treated in a number of different ways, that the upper and lower gums are treated alternatively at rapidly following intervals and while the housing of the tooth brush need not change its position with reference'to the mouth, and that the wear on the bristles is uniform or substantially uniform.

A further very important object of the invention is to provide a cordless automatic tooth brush for massage of gums and for simultaneous cleaning of teeth whereby the gums are automatically massaged in such a way that the bristles tend to shift the upper gums toward the roots of the upper row of teeth and to shift the lower gums toward the roots of the lower row of teeth.

An additional object of my invention is to provide a very simple, compact, easy-to-handle, eye-pleasing and comparatively inexpensive automatic tooth brush of the above outlined characteristics which may be used by children and/or adults, which is constructed and assembled in such a way that all of its current-conveying elements are protected against contact with water, and wherein the bristle-carrying part may be readily separated from the remainder of the brush so that such bristlecarrying part may be replaced by a new one or that each member of the family may use the same basic structure with a different bristle-carrying part.

Still another object of the invention is to provide a very simple transmission mechanism which connects the bristle-carrying part with the electric motor and which insures that the bristles will treat the gums and the teeth in the above outlined manner whereby the upper and lower gums are massaged alternatively and at rapidly following intervals.

A concomitant object of the invention is to provide a tooth brush of the above outlined characteristics which 3,233,265 Patented F eb. 8, i966 ice is constructed and assembled in such a way that its bristles are free to engage the gums only at the time when they are moving in directions in which their massaging action is beneficial to the gums and to remain out of contact with the gums when they travel in directions in which their massaging action is less desirable.

A further object of the invention is to provide a novel switch which may be used in a cordless electric tooth brush of the above outlined characteristics and to provide a novel housing which embodies the improved switch so that the two parts form an integral unit which prevents moisture from reaching the conductors.

Another very important object of my invention is to provide an automatic tooth brush wherein all movements of the bristle-carrying brush member are positively guided at all times so that the direction of movement of bristles with reference to the gums and/or with reference to the teeth is fully controlled to insure optimum cleansing and massaging action.

A further object of the invention-is to provide an automatic tooth brush wherein the bristle-carrying part is always held against uncontrolled or uncontrollable vibrations, wherein the bristle-carrying part may be removed or reinserted into the housing with little loss in time and by exertion of small forces, and wherein the housing is configurated in such a way that it may be grasped and the power plant controlled by a single band of the user.

An additional object of the invention is to provide an automatic tooth brush which may be manipulated with little effort on the part of the user so that it may be used for comparatively long periods of time without causing tiredness of the arm, and which may be provided with its own readily accessible and readily renewable source of electrical energy so that it can be used without cords.

With the above objects in view, one feature of my invention resides in the provision of an automatic tooth brush which comprises essentiallya brush member including an elongated handle having a front section provided with laterally extending bristles, a source of power preferably including a small electric motor accommodated in a housing which receives with some play the other end portion of the handle, and a transmission which is driven by the motor and which is arranged to oscillate the bristles through the intermediary of the handle about an axis which is substantially parallel with the handle and to simultaneously oscillate the bristles in a direction which is substantially prependicular to the handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to the handle.

In a preferred construction of my automatic tooth brush, the transmission comprises two levers the. first of which is coupled to the other end portion of the handle and serves to oscillate the bristles about the axis which is parallel with the handle and the second of which is coupled to an intermediate portion of the handle or to an intermediate portion of the first lever to oscillate the bristles in directions at right angles to the axis of the handle. Such parallel axis may coincide with or may be slightly spaced from the axis of the handle.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved tooth brush itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon persual of the following detailed description of certain specific embodi- 3 ments with reference to the accompanying drawings, in which:

FIG. 1 is a schematic front end view of a portion of an automatic tooth brush which embodies one form of my invention;

FIG. 1a is a schematic vertical section through the gums and through the two rows of teeth which may be massaged and cleaned by the tooth brush of FIG. 1;

FIG. 2 is a diagrammatic perspective view of the tooth brush substantially as seen in the direction indicated by an arrow 2 shown in FIG. 1;

FIG. 3 is a schematic front elevational View of a portion of a modified automatic tooth brush wherein the circular cylindrical cam, used in the tooth brush of FIG. 1, is replaced by a cam of substantially triangular outline;

FIG. 4 is a diagrammatic perspective view of a third automatic tooth brush;

FIG. 5 is a longitudinal section through a working model of the third tooth brush, the section of P16. 5 being taken in the direction of arrows as seen from the line 5-5 of FIG. 6;

FIG. 6 is a horizontal section through the structure shown in FIG. 5;

FIG. 7 is a transverse section as seen in the direction of arrows from the line 77 of FIG. 6;

FIG. 8 is an end view as seen from the left-hand side of FIG. 5 or 6; and

FIG. 9 illustrates in longitudinal section a small portion of a modified automatic tooth brush wherein the housing is integral with a starter switch.

Referring to the drawings, and first to FIGS. 1 and 2, there is shown an automatic tooth brush comprising a brush member 10 which includes an elongated handle 11 having a front section forming a back support 11a and laterally extending bristles 12. It should be noted that, in FIG. 1, the longitudinal extension of the handle 11 is perpendicular to the plane of the drawing and that the bristles 12 are located in planes which are parallel to the plane of FIG. 1. The rear end portion of the handle 11 is rigidly secured to or integral with a two-armed lever 13 which is oscillatable about the axis of a pivot pin 14, and this axis is substantially parallel with the axis of the handle 11 and with a working plane A, i.e., with a plane which is common to the exposed surfaces of teeth and gums (see FIG. la). The pin 14 is slightly spaced from the handle 11 and is carried by a second lever 15 one end of which is fixed to the housing H of the tooth brush by a pivot pin 16. The other end of the lever 15 is bifurcated, as at 17, and accommodates a circular cylindrical eccentric cam 18. The axis of the pin 14 is parallel with the axis of the pin 16. The free end of the longer arm of the lever 13 is connected to a pivot pin 19 which is parallel with the pins 14, 16 and which is provided at one end of a motion transmitting link 2%. The other end of this link is secured to an eccentric pivot pin 21 provided on a disk-shaped gear 22. The gear 22 is provided with an annulus of teeth 23 meshing with the teeth of a pinion 24 which is rigid with the eccentric 13 and which is rotatable with a shaft 25. The gear 22 is rotatable about the axis of a shaft 22a. The number of teeth 23 and this axis is substantially parallel with the axis of the handle 11 and with a working plane A, i.e., with a plane which is common to the exposel surfaces of teeth and gums (see FTG. 1a). The pin 14 is slightly spaced from the handle 11 and is carried by a second lever 15 one end of which is fixed to the housing H of the tooth brush by a small electric motor M shown in FIG. 2. The pinion 24 then rotates in a counterclockwise direction (arrow Z and the gear 22 rotates in a clockwise direction (arrow The toothbrush of FIGS. 1 and 2 operates as follows: In FIG. 1, the lever 15 is located midway between its end positions, and it will be noted that this lever is oscillatable in directions indicated by a double-headed arrow 4 x, namely, substantially at right angles to the axis of the handle 11. The lever 13 is oscillatable in directions indicated by a double-headed arrow y and causes the bristles 12 to rock about the axis of the pin 14 which is parallel with the axis of the handle 11. FIG. 1 illustrates the brush member 111 in one of its end positions, namely, in a position corresponding to such angular po sition of the gear 22 in which the pin 21 is nearest to the pin 14. The tips of the median row of bristles 12 then extend along a line a shown in FIG. 1. The teeth 23 of the gear 22 mesh with the teeth of the pinion 24 and, when the latter rotates through an angle of degrees (arrow 2 the lever 15 reaches one of its end positions while the gear 22 turns through 45 degrees (arrow 2 and moves the pin 21 to the phantom-line position 21b. The tips of the median row of bristles 12 are then 10-- cated on a line b shown in FIG. 1. The lines a and if intersect an arcuate path B which is the ideal path of the bristle tips when the tooth brush is in actual use. When the pinion 24 rotates through another angle of 90 degrees (arrow Z the pin 21 reaches the phantom-line position 210 and the tips of the median row of bristles 12 reach the line c which intersects the path B. The lever 15 has returned to its median position corresponding to that shown in FIG. 1, and the lever 13 also takes a median position in which its longitudinal extension is substantially perpendicular to the longitudinal extension of the lever 15. Thus, when the tips of the median row of bristles 12 extend along the line 0, the line connecting the axes of the pins 14, 19 is substantially horizontal, as viewed in FIG. 1. The cam 18 has reached its lower end position and its axis is nearest to the pin 14. As the pinion 24 continues to rotate through consecutive angles of 90 degrees, the tips of the median row of bristles 12' successively reach the positions indicated by lines d, e, f, g, h and i whereby the line i coincides with the line a. FIG. 1 shows that the path B, in which the tips of the bristles 12 travel, resembles the numeral eight whereby the line c coincides with the line g. In other words, the path B resembles a higher plane curve known as lemniscate. It will be noted that the path B is located in a plane which is substantially perpendicular to the axis (longitudinal extension) of the handle 11. FIG. 1 reveals further that the bristles 12 will press against the gums and against the exposed surfaces of the teeth while their tips travel from the line a to the line c or from the line e to the line g, and that the tips of the bristles will be or preferably are spaced from the gums and from the teeth while travelling from the line 0 to the line 2 and from the line g to the line i. It is assumed, of course,- that the housing H of the tooth brush is held at a con-- stant distance from the mouth. Now, and since the two rows of teeth are assumed to be located along the line 0 or g (and more particularly along that section of the path B which extends between the lines bc and f-c), the bristles 12 will massage the gums (located substantially along that portion of the path B which extends between the lines ab and e-f) in a sense to tend to shift the upper gums toward the upper row of teeth (while the bristle tips travel from a to c) and to tend to shift the lower gums against the lower row of teeth (while the bristle tips travel from e to g).

The above-described action of the bristles 12 upon the gums and upon the teeth will be more clearly understood with simultaneous reference to FIGS. 1 and 1a. FIG. 1a shows the upper gums UG, the lower gums LG, the upper row of teeth UT, the lower row of teeth LT, and the working plane A. When the bristles 12 travel from the line a to the line b, they sweep along the exposed surfaces of the upper gums UG and tend to move these gums toward the roots of the upper row of teeth UT by simultaneously advancingall food rests into that area of the mouth from which such food rests may be flushed out with water and tooth paste. While travelling from the line b to the line c, the bristles 12 clean the. teeth UT and travel toward the lower row of teeth LT. In the next stage, and while travelling from c to d and thereupon to e, the tips of the bristles 12 move away from the teeth LT and from the lower gums LG to reach the lower gums somewhere along the line e. The action of the bristles 12 is then repeated in reverse, i.e., while travelling from e to f, the tips of the bristles sweep along the exposed surfaces of the lower gums LG and tend to displace these gums toward the roots of the lower row of teeth LT by simultaneously advancing any food rests into more readily accessible areas of the mouth cavity. In the next stage, the tips of the bristles clean the teeth LT by travelling upwardly from the line 1 to the line g to thereupon move away from the teeth UT and from the gums UG while their tips travel from g to h and thereupon to i, i.e., back to the line a to repeat the massaging and cleaning operations in the above described way as long as the motor continues to drive the pinion 24. It is well known that a brush with comparatively stiif bristles is likely to cause bleeding of gums if the bristles are allowed to push the gums in a direction away from the roots of adjacent teeth.

Of course, the bristles 12 are flexed so that they sweep along the exposed surfaces of the gums UG, LG and teeth UT, LT whereby their tips actually travel along a path which is defined by the major portion of the path B and by the two arcuate sections A A of the surface A. When the tooth brush is in use, the teeth UT and LT are cleaned in a direction from the roots toward the crowns of the respective teeth (while the tips of the bristles 12 travel from b to c and from f to g), and it was found that the cleaning and massaging action is particularly satisfactory if the brush member 1t) is placed against the teeth in such a way that the bristles are inclined upwardly with reference to a horizontal plane when their tips are placed against the upper gums UG or, analogously, that the bristles 12 are inclined downwardly with reference to a horizontal plane when their tips are placed against the lower gums LG. If applied in this manner, the bristles will be flexed while their tips travel from a to c and from e to g but will be allowed to straighten out while travelling from c to e or from g to i.

It was also found that the cleaning and massaging action of the brush member is quite satisfactory if the pinion 24 is driven at such a speed that the lever is rocked at a frequency of 10-20 oscillations per second (arrow x) and that the lever 13 is rocked at a frequency of 5-10 oscillations per second (arrow y). The composite movement of each bristle tip in response to such oscillations of the levers 13, 15 then results in a movement of their tips along the lemniscate path B or, more particularly, along the path B modified in view of the position of the surface A.

FIG. 3 illustrates a portion of a slightly modified automatic tooth brush which differentiates from the tooth brush of FIG. 1 merely in that the circular eccentric cam 18 is replaced by a different cam 26 which is of generally polygonal, i.e., triangular shape and which causes the tips of the bristles 12 to travel along a slightly different lemniscate path 3,. A feature of the apparatus shown in FIG. 3 is seen to reside in that the tips of the bristles 12 move very rapidly into and out of contact with the gums and teeth of the user. This will be readily understood by comparing the path B with the path B Thus, and while moving toward and away from the line c shown in FIG. 3, the tips of the bristles move nearly perpendicularly with reference to the curve A, and the same holds true when the tips of the bristles move toward or away from the lines a and e Many other types of polygonal cams may also be used as substitutes for the cams 18 or 26.

FIG. 4 illustrates a third automatic tooth brush which comprises a brush member 10 having bristles 12, a back support 11a for the bristles and an elongated handle 11 having its rear end portion connected with a first lever 27. The handle 11 is rotatable in a bearing sleeve 28 provided at one end of a second lever 30 whose other end is secured to a pivot pin 29 mounted in the housing of the tooth brush. A median portion of the lever 30 is rigidly connected to one end of a motion transmitting link 31 the other end of which is bifurcated, as at 32, and receives a circular cylindrical eccentric cam 34 mounted on the shaft 33 of a pinion 35 which meshes with a gear 36 corresponding to the gear 22. The pinion 35 and gear 36 respectively rotate in directions indicated by arrows Z and Z The number of teeth on the gear 36 is twice the number of teeth on the pinion 35, i.e., the r.p.m. of the pinion 35 is twice the r.p.m. of the gear 36. The gear 36 carries an eccentric crank pin 37 which extends into a cam slot 3% provided at the free end of the lever 27 so that, when the gear 36 rotates, the bristles 12 are caused to oscillate in directions indicated by the arrow y. The cam 34 causes the bristles to oscillate in directions indicated by the arrow x. In following the movements of the lever 27, the handle 11' turns back and forth in the interior of and about the axis of the bearing sleeve 28 and, in following the movements of the lever 30, the handle 11' rocks with the bearing sleeve about the axis of the pin 29.

The shaft 33 is driven by a source of power 39, here shown as an electric motor, through a reducing gear including a pinion 40 on the output shaft 39a of the motor 39 and a gear 41 on the shaft 33. The ratio of the gears 40, 41 is selected in such a way that the bristles 12 oscillate at a desired frequency so that the two oscillatory movements of the bristles are superimposed on each other whereby the bristle tips travel in a lemniscate path which is located in a plane that is perpendicular to the handle 11'.

The operation of the tooth brush shown in FIG. 4 is basically the same as that of the tooth brush shown in FIGS. 1 and 2 or in FIG. 3. The motor 39 drives the shaft 33 which in turn drives the cam 34 and the pinion 35 so as to rotate the gear 36 (arrow Z2). The cam 34 causes the lever 33 to rock back and forth about the axis of the pin 29 so that the bearing sleeve 28 follows such movement and causes the bristles 12 to oscillate in directions indicated by the double-headed arrow x. Such movement causes the bristles 12 to move into and out of contact with the gums and teeth. The gear 36 drives the crank pin 37 and causes the lever 27 to rock 'back and forth about the axis of the handle 11 so that the bristles 12 oscillate in directions indicated by the double-headed arrow y. Such movement causes the bristles to massage the gums and to clean the teeth. In other words, the lever 34 causes the bristles to knock against the teeth and against the gums, whereas the lever 27 causes the bristles to massage the gums and to clean the teeth by causing the bristles to sweep along the gums and along the exposed surfaces of the teeth in a manner substantially as described in connection with FIG. 1a.

FIGS. 5 to 8 illustrate a working model of an automatic tooth brush which is constructed in a manner as outlined in connection with FIG. 4. The tooth brush comprises an elongated housing or casing 42 which is provided with a transverse partition 43 so that the interior of the housing defines a front chamber 44 and a rear chamber 45. The housing 42 is comparatively flat in that its width (as seen in a direction at right angles to the longitudinal extensions of the bristles 12) exceeds its height, see particularly FIG. 8. In other words, the configuration of the housing 42 resembles the configuration of the handle in a conventional manually reciprocable tooth brush.

The rear chamber 45 accommodates one or more sources of electrical energy here shown as batteries 46. In the illustrated embodiment, the chamber 45 accommoda-tes three parallel rod-shaped batteries whose axes are parallel with the longitudinal extension of the housing 42, i.e., with the axis of the handle 11. The mannor in which the electric motor 39 is connected in circuit with one, two or all three batteries 46 is well known in the art and is not fully shown in the drawings, Themotor 39 is located immediately in front of the partition 43 and its axis is perpendicular to the longitudinal exten sion of the housing. In addition to the motor 39, the: front chamber 44 accommodates various gears, levers and other parts of the transmission mechanism which serves to oscillate the bristles 12 in directions indicated by the double-headed arrows x and y. The ends of the shaft 33 are journalled in the side Walls of the housing 42 and the axis of this shaft is parallel with the axis of the output shaft 39a. As best shown in FIGS. 6 and 7, the shaft 33 carries the gear 41 which mates with the pinion 4d, the cam 34 which extends into the bifurcated end portion 32 of the lever 31, a spacer sleeve .47 which abuts against one end face of the cam 34, and the pinion35 which meshes with the gear 36. The gear 36 is mounted on a stub shaft 48 which is journalled in one side wall of the housing 42. If. desired, the parts 41, 34, 47 and 35 may form a rigid unit or may be made of a single: piece of suitable metallic or plastic material. The crank. pin 37 is mounted in the gear 36 and cooperates with the lever 27.

The pin 29 is parallel with the shaft 33and is located; at the forward end of the chamber 44, see particularly FIG. 5. It will be noted that this pin 29 is located at that side of the handle 11' which is nearer to the bristles 12 and that its ends are journalled in the side walls of the housing 42. The lever 30 is rigid with the link 31 and carries the bearing sleeve 28.

The handle 11' of the brush member 10' comprises several sections including an intermediate section or boss 49 which is integral with an annular rear section 50. The section surrounds the bearing sleeve 28 in such a way that the sleeve is held against axial movement with respect thereto. The section 49 is provided with an axially extending blind bore which receives an elongated bearing pin 51 extending coaxially through the sleeve 28 and rearwardly intoa through bore provided in a transverse wall at the rear end of the annular section 54 The section 49 is free to rock about the axis of the pin 51. The annular section 50 is integral with the lever 27 which is formed with the aforementioned cam slot 38 to receive thefree end of the crank pin 37 so that, when the gear 36 rotates, the lever 27 and the sections 49, 545 oscillate about the axis of the bearing pin 51 to move the bristles 12 in directions indicated by the doubleheaded arrow y. An annular sealing diaphragm 52 is slipped onto the section 49 and surround-s the front end portion or neck 53 of the housing 42 so as to prevent entry of moisture or solid matter into the front chamber 44. This diaphragm is dimensioned in such a way that it allows the handle 11' to perform oscillatory movements in directions indicated by the double-headed arrows x and y. A detachable tubular cap or hood 54 may but need not be provided on the front end portion of the housing 42 to conceal the diaphragm 52 and to further reduce the likelihood that water, tooth paste or other matter could penetrate into the chamber 44. The diaphragm v52 allows for cleaning of bristles 12 in a stream of water issuing from a faucet while the handle 11' remains attached to the housing 42.

The front end portion 55 of the section 49 is of slightly conical shape and is inserted into the foremost section 56 of the handle 11'. This section 56 is provided with a blind bore 57 which tapers in a direction toward the bristles 12 sothat it may receive the end portion 55 with requisite friction but that it still allows for rapid and convenient separation of bristles 12 and back support 11a from the remainder of the tooth brush. Thisis necessary to facilitate more convenient cleaning of bristles 12 and to reduce the overall dimensions of the tooth brush when not in actual use. Furthermore, the tooth bru h n rma ly turn s a w t tw o m r sections 56 so that an entire family may .use the same housing whereby each member of the family owns an attachment such as the section 56 including a back support 11a and bristles 12. The section 56 preferably consists of transparent or transulcent synthetic plastic material with the bristles permanently embedded therein in a manner well known in the art. It will be noted that the housing 42 receives the handle 11' with sufiicient play so that the bristles 12 may oscillate in response to movement of the levers 27 and 30 when the circuit of the motor 39 is completed.

The means for starting or arresting the motor 39 comprises a pushbutton switch including a member 58 which cooperates with normally open contacts connected in circuit with the motor and with the batteries 46. The switch member 58 is preferably mounted in the region which is in the range of the index finger when the housing 42 is grasped by the right hand of the user. The inner side of the switch member 58 carries a fluidtight diaphragm .59 which is bonded or otherwise secured to the inner side of the housing 42 so that no moisture can reach the contacts 60. The member 58 extends through an opening 42d provided in the side wall of the housing.

The housing 42 preferably consists of synthetic plastic material and, in order to eliminate the diaphragm 59 :and opening 42d, I also contemplate utilizing a slightly modified housing 42' of the type shown in FIG. 9. This housing comprises a wall portion 42a which carries one of the contacts 60' and which is so thin that it may be flexed by fingerpressure (arrow 61) so as to replace the member 58 and, when necessary, to complete the circuit of the motor 39, not shown in FIG. 9. The material of the housing 42' is sufiiciently elastic to insure that the wall portion 42a acts not unlike a diaphragm and automatically returns tothe position of FIG. 9 to open the circuit of the motor as soon as it is released by the finger. Other types of switches may be used if desired.

It goes without saying that the tooth brush shown in FIGS. 48 and 9 may be modified by utilizing batteries whose axes are parallel with the axis of the motor 39 or by providing the housing 42 or 42' with a suitable cable so that the motor 39 may be driven from a remote soure of electrical energy.

A very important advantage of my tooth brush is that the bristles are permitted to remain in contact with the gums only at such times when their massaging effect is actually beneficialto the gums, i.e., when they tend to shift the upper gums UG toward the roots of the upper row of teeth UT and when they tend to shift the lower gums LG toward the roots of the lower row of teeth LT. Of course, the tooth brush must be moved back and forth along the line extending between the crowns of the teeth UT and LT, but all other movements are performed in a fully automatic way in that the tips of the bristles travel in the path B or B and perform massaging actions which alternate with cleaning actions, i.e., after massaging the upper gums UG, the bristles will clean the teeth UT prior to massaging the lower gums LG, and this action is followed immediately by a cleaning of the teeth LT. The operation is then repeated many times in the same sequence. All that the user has to do is to hold the housing and to move the brush member 10 or 10', either continuously or at intervals, along the line between the crowns of the teeth UT and LT. The stroke of the lever 13 or 27 is selected with a view to insure that the distance between the lines a and e in FIG. 1 or between thelines a and e in FIG. 3 (and the corresponding lines intersecting the path of the bristles 12 in the tooth brush of FIGS. 48) suffices for satisfactory treatment of the gums UG and LG without moving the housing up and down, i.e., without moving the housing vertically, as viewed in FIG. 111.

If desired, the tooth brush of my invention may be used without tooth paste, to wit: for the sole purpose of strengthening the gums.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapted for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles; a source of power; and a transmission driven by said source and arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction which is substantially perpendicular to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

2. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles; a source of power; and a transmission driven by said source and arranged to oscillate said bristles through the intermediary of said handle about an axis extending at least substantially in direction ofsaid handle and simultaneously oscillate said bristles in a direction which is substantially transversal. to said handle and at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

3. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles; a source of power; and a transmission driven by said source andarranged to oscillate said bristles through the intermediary of said handle at a first frequency about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction which is substantially perpendicular to said handle and at a second frequency which is twice said first frequency so that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

4. An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section extending with play into said housing; a motor provided in said housing and having a rotary output shaft; and a transmission arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction which is substantially perpendicular to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle, said transmission being mounted in said housing and comprising a first lever rigid with said handle and arranged to rock about said axis, a rotary disk-shaped member driven by said output shaft, a link eccentrically coupled to said disk-shaped member and articulately connected with said lever to rock the lever about said axis and to thereby oscillate the tips of said bristles, a second lever having a median portion articulately connected with said first lever, a pivot fixed to said housing and secured to one end of said second lever, and a cam driven by said output shaft and operatively connected with the other end of said second lever so as to rock said second lever about said pivot and to thereby oscillate the tips of said bristles in the planes of the respective lemniscate curves and substantially at right angles to the direction of oscillation in response to rocking of said first lever.

5. An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section extending with play into said housing; a motor provided in said housing and having a rotary output shaft; and a transmission arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially perpendicular to said handle, said transmission being mounted in said housing and comprising a first lever rigid with said handle and arranged to rock about said axis, a rotary disk-shaped member driven by said output shaft, a link eccentrically coupled to said diskshaped member and articulately connected with said lever to rock the lever about said axis and to thereby oscillate the tips of said bristles, a second lever having a first end portion, a median portion articulately connected with said first lever, and a bifurcated second end portion, a pivot fixed to said housing in parallelism with said axis and connected with the first end portion of said second lever, and a circular cylindrical eccentric cam driven by said output shaft and received in said bifurcated end portion to rock said second lever about said pivot when said motor is in operation and to thereby oscillate the tips of said bristles in the planes of the respective lemniscate curves and substantially at right angles to the direction of oscillation in response to rocking of said first lever.

6. An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section extending with play into said housing; a motor provided in said housing and having a rotary output shaft; and a transmission arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction which is substantially perpendicular to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle, said transmission being mounted in said housing and comprising a first lever rigid with said handle and arranged to rock about said axis, a rotary disk-shaped member driven by said output shaft, a link eccentrically coupled to said disk-shaped member and articulately connected with said lever to rock the lever about said axis and to thereby oscillate the tips of said bristles, a second lever. having a first end portion, a median portion articulately connected with said first lever, and a bifurcated second end portion, a pivot fixed to said housing and connected with the first end portion of said second lever, and an eccentric cam of polygonal outline, said cam being driven by said output shaft and being received in said bifurcated end portion to rock said second lever about said pivot and to thereby oscillate the tips of said bristles in the planes of the respective lemniscate curves and substantially at right angles to the direction of oscillation in response to rocking of said first lever.

7. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section; a housing having internal chamber means and comprising an end portion receiving with play the rear section of said handle; an electric motor received in said housing and having an output shaft; battery means accommodated in said housing and connected in circuit with said motor; and a transmission driven by said output shaft and arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction at right angles to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

8. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section; a housing defining a front chamber, a rear chamber and comprising an end portion communicating with said front chamber and receiving with play said rear section; an electric motor received in said front chamber and having an output shaft; battery means provided in said rear chamber and connected in circuit with said motor; and a transmission provided in said front chamber, said transmission being driven by said output shaft and being arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction at right angles to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

9. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section; a housing having internal chamber means and comprising an end portion receiving with play the rear section of said handle; an electric motor received in said housing and having an output shaft; battery means accommodated in said housing and connected in circuit with said motor; a normally open manually operable switch provided on said housing and connected in circuit with said motor and with said battery means so as to complete said circuit and to start said motor in response to manual operation thereof; and a transmission driven by said output shaft and arranged to oscillate said bristles through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously oscillate said bristles in a direction at right angles to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle.

10. An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section extending with play into said housing; a motor provided in said housing and having a rotary output shaft disposed substantially at right angles to said handle; and a transmission arranged to impart to said bristles an oscillatory movement through the intermediary of said handle about an axis which is substantially parallel with said handle and to simultaneously impart to said bristles a second oscillatory movement in a direction which is substantially perpendicular to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle, said transmission being mounted in said chamber means and comprising a pair of levers each arranged to be rocked by said output shaft and each arranged to impart to the bristles one of said oscillatory movements.

11. An automatic tooth brush as set forth in claim 14 wherein said transmission further comprises a second shaft parallel with said output shaft and operatively connected with said levers, and mating reducing gears provided on said shafts to drive said second shaft at a predetermined speed.

12. An automatic tooth brush as set forth in claim 11, wherein said transmission further comprises a pinion mounted on said second shaft, a gear meshing with said pinion, an eccentric crank pin provided on said last named gear, and a driving connection between said crank pin and one of said levers.

13, An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and an annular rear section extending with play into said chamber means; a motor provided in said chamber means; and a transmission arranged to impart to said bristles a first oscillatory movement through the intermediary of said handle and about an axis which is substantially parallel with said handle and to simultaneously impart to said bristles a second oscillatory movement in a direction substantially at right angles to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to said handle, said transmission being mounted in said chamber means and comprising a pair of levers rockable by said motor and each arranged to impart to the bristles one of said oscillatory movements, one of said levers being connected with said rear section.

14. An automatic tooth brush as set forth in claim 13, wherein said one lever is arranged to oscillate the bristles about said axis and wherein said transmission further comprises a bearing sleeve received in said annular section and a bearing pin extending through said bearing sleeve and into said rear section so that the handle is rockable about said pin, the other lever being connected with said bearing sleeve.

15. An automatic tooth brush as set forth in claim 14, wherein said transmission further comprises a pivot member anchored in said housing, one end of said other lever being mounted on said pivot member and said transmission also comprising a link rigid with said other lever and driven by said motor to rock said other lever about said pivot member.

16. An automatic tooth brush, comprising a housing defining internal chamber means; a brush member including an elongated handle having a front section provided with laterally extending bristles and an annular rear section extending with play into said chamber means; a motor provided in said chamber means; and a transmission arranged to impart to said bristles a'first oscillatory movement through the intermediary of said handle and about an axis which is substantially parallel with said handle and to simultaneously impart to said bristles a second oscillatory movement in a direction substantially at right angles to said handle at such frequency that the tip of each bristle travels in a lernniscate path in a plane which is substantially perpendicular to said handle, said transmission being provided in said chamber means.

17. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles and a rear section; a housing arranged to be grasped by hand and defining an internal chamber receiving with play the rear section of said handle; motor means provided in said chamber; and a transmission provided in said chamber, said transmission being operatively connected with said motor and being arranged to impart to said bristles a first oscillatory movement through the intermediary of said handle and about an axis which is substantially parallel with and closely adjacent to the axis of said handle and to simultaneously impart to said bristles a second oscillatory movement in a direction substantially at right angles to said handle at such frequency that the tip of each bristle travels in a lemniscate path in a plane which is substantially perpendicular to the handle so that, when the brush is in actual use, the bristles will tend to move into and out of contact with the gums and teeth and will tend to shift the gums toward the roots of the respective teeth.

18. An automatic tooth brush as set forth in claim 17, wherein said bristles are inclined with reference to the upper and lower gums when the brush is in use and when the tips of the bristles reverse the direction of their movement at the ends of the respective paths.

19. An automatic tooth brush, comprising a brush member including an elongated handle having a front section provided with laterally extending bristles; a source of power; and a transmission driven by said source and arranged to oscillate said bristles through the intermediary of said handle at a first frequency about an axis which is substantially parailel with said handle and to simultaneously oscillate said bristles in a direction which is substantially perpendicular to said handle and at a second 13 14 frequency which is twice said first frequency so that the References Cited by the Examiner tip of each bristle travels in a predetermined path in a UNITED STATES PATENTS plane which is substantially perpendicular to said handle. 2,935,072 5/1960 Jones at all 15 22 X 29. An automatic toothbrush as set forth 1n claim 17, 3,159,859 12/1964 Rasmussen 15 22 wherein said bristles are inclined with reference to the 5 3160902 12/1964 Aymar upper and lower gums when the brush 15 in use and when the tips of the bristles reverse the direction of their move- FOREIGN PATENTS ment at the ends of the respective paths, such inclination 577,198 5/1958 Italy.

of said bristles with respect to the upper and lower gurus varying during movement of said bristles from the one 10 CHARLES A'WILLMUTHPWMW to the other of said ends of the respective paths. EDWARD L. ROBERTS, Assistant Examiner. 

1. AN AUTOMATIC TOOTH BRUSH, COMPRISING A BRUSH MEMBER INCLUDING AN ELONGATED HANDLE HAVING A FRONT SECTION PROVIDED WITH LATERALLY EXTENDING BRISTLES; A SOURCE OF POWER; AND A TRANSMISSION DRIVEN BY SAID SOURCE AND ARRANGED TO OSCILLATE SAID BRISTLES THROUGH THE INTERMEDIARY OF SAID HANDLE ABOUT AN AXIS WHICH IS SUBSTANTIALLY PARALLEL WITH SAID HANDLE AND TO SIMULTANEOUSLY OSCILLATE SAID BRISTLES IN A DIRECTION WHICH IS SUBSTANTIALLY PERPENDICULAR TO SAID HANDLE AT SUCH FREQUENCY THAT THE TIP OF EACH BRISTLE TRAVELS IN A LEMNISCATE PATH IN A PLANE WHICH IS SUBSTANTIALLY PERPENDIULAR TO SAID HANDLE. 